The present disclosure relates to a light emitting diode driver capable of stably controlling current flowing in a light emitting diode channel.
Recently, a light emitting diode (LED) is attracting attention and demanded increasingly.
A device employing such a light emitting diode may be manufactured to be compact, such that it may be accommodated in a relatively small space in which existing electronic devices may not otherwise be able to be accommodated. Further, when such a light emitting diode is used as an illumination apparatus, it is easy to implement the emission of various colors of light and adjust the luminance thereof, such that the light emitting diode may be used in an apparatus for an illumination system appropriate for a situation such as watching a movie, reading, or holding a conference.
In addition, the light emitting diode consumes an amount of power corresponding to ⅛ of the power consumed by a incandescent lamp, has a lifespan of fifty thousand to a hundred thousand hours, 5 to 10 times longer than that of an incandescent lamp, is environmentally-friendly, as a mercury-free light source, and allows for design freedom.
Due to such advantages, LED illumination apparatus development projects have been implemented as nationally-funded projects in many nations, such as the United States of America, Japan and Australia, as well as the Republic of Korea.
Further, recently, as flat panel display technology has evolved, flat panel displays are being employed in instrument clusters for vehicles, as well as in smartphones, game consoles, and digital cameras. In the future, display devices are expected to be more widely utilized in our daily lives, such as in an ultra-thin televisions and transparent navigation devices.
Currently, in the field of displays, relatively new flat panel display (FPD) technology, which meets the requirements of the present era for multimedia displays having features such as high-resolution and large screen sizes, dominates. Particularly, in the large display market, liquid crystal display (LCD) televisions have rapidly grown in popularity, and thus, such a LCD TV is expected to lead the market in terms of price and marketability.
As the flat panel display, a thin film transistor liquid crystal display (TFT-LCD) is mainly used.
Such a TFT-LCD includes a backlight unit emitting light and usually uses cold cathode fluorescent lamps (CCFL) as a back light source. However, recently, LEDs have been used therein, thanks to various advantages such as low power consumption, a long lifespan, and environmentally-friendly characteristics.
Therefore, a relatively inexpensive electronic power system for a backlight unit power module using an LED and an appropriate control element therefor.
An LED as described above requires a driver for the driving thereof. Previously, a switching element has been used to maintain current flowing through LED channels at a constant level. As disclosed in Patent Document 1, a detection resistor may be disposed between one terminal of a switching element and ground in order to maintain the amplitude of current flowing through a plurality of LED channels at a constant level.
Such a resistor has a constant resistance value. In order to detect a current, an amount of power corresponding to the resistance value is consumed, and heat is generated, so that power efficiency may be lowered. If a detection resistor having a low resistance value is used for this purpose, however, the detection voltage level may be so low that an offset may occur, such that it may be difficult to stably control the current flowing through LED channels.